Coniferous Forest Soil

Soil containing a mixture of clay, sand, silt, and humus. good for growing most crops.

sandy soil

Soil containing notably more sand. Sandy soils are easy to work, but water flows rapidly through them.

clay soil

Soil with very small, easily compacted particles; form large, dense clumps when wet. Clay soils are more porous and hold water better than sandy soils, but have low permeability (small pores).

silt

Fine soil particles

soil porosity

Percentage of space in rock or soil occupied by voids whether the voids are isolated or connected.

soil permeability

Rate at which water and air move from upper to lower soil layers.

Soil Texture

Nutrient-Holding Capacity

Water-Infiltration Capacity

Water-Holding Capacity

Aeration

Workability

Clay

Good

Poor

Good

Poor

Poor

Silt

Medium

Medium

Medium

Medium

Medium

Sand

Poor

Good

Poor

Good

Good

Loam

Medium

Medium

Medium

Medium

Medium

A high or low ph affects the plants' ability to take up nutrients. Humus helps retain water and water-soluble nutrients, which can be taken up by plant roots.

Wind and, more commonly, water erode the soil, often pouring it into waterways. The loss of topsoil results in less fertile land and the eroded sediment, the largest source of water pollution, clogs the waterways. The water becomes cloudy, fish die, and flood risk increases. If soil erodes faster than it is formed, it becomes a nonrewable resource. Annual erosion rates for farmlands around the world are 7-100 times the natural renewal rate. We are losing 7% of our topsoil each decade; this has slowly disastrous effects on agriculture. In the US, the Dust Bowl years spurred government action to promote soil conservation. However, while this has improved the situation somewhat, it's still dire: we have lost large percentages of our topsoil over the years, and are losing vast amounts each year.

People are not aware of soil erosion because it is such a gradual process.

desertification

Conversion of rangeland, rain-fed cropland, or irrigated cropland to desertlike land, with a drop in agricultural productivity of 10% or more. It is usually caused by a combination of overgrazing, soil erosion, prolonged drought, and climate change.